Nanotubes suppress immune response of human lung cells.

Mar 06, 2009

Herzog, E, HJ Byrne, A Casey, M Davoren, A-G Lenz, KL Maier, A Duschl and GJ Oostingh. 2009. SWCNT suppress inflammatory mediator responses in human lung epithelium in vitro. Toxicology and Applied Pharmacology 234:378-390.

Synopsis by Stacey L. Harper

Extremely small carbon nanotubes can move through lung fluid and suppress normal immune responses in human lung cells, finds this laboratory study.

A nanomaterial prized for its potential use in electronics moved through human lung fluid and altered the way lung cells reacted to infections, possibly reducing their ability to signal immune defenders and fight off the invaders.

The results add more concern about the safety of the very tiny particles called single-walled carbon nanotubes (SWCNT). Workers who make the materials -- and consumers who use them -- may be at risk if the nanomaterials are inhaled.  

If breathed in, the materials may make the immune system less responsive to infections, suggest the authors. This could lead to more and longer respiratory diseases in those exposed to the fibrous particles.

SWCNT and other nanomaterials are very small particles, in the neighborhood of one billionth of a meter. Their small size gives them properties not found in their larger counterparts. SWCNTs are being investigated for use in electronics, transparent conducting films and building materials such as ultra-tough fibers.

While the new materials are expected to provide many benefits, the full impact on society should take into consideration negative consequences of material production and release into the environment. Slight modifications of the surface chemistry are known to alter the properties of the materials and may offer a way to modify their toxic interactions with living systems.

This study directly compared the effects from SWCNT exposure to a more classically-known asbestos exposure.  Asbestos is used as a reference material since SWCNTs and asbestos have similar dimensions and are both fibers that could get stuck and stay deep in the lungs. 

The researchers examined how the extra-small particles impact life by looking at how lung cells respond when in contact with the particles.  They found that the SWCNTs were more lethal to cells than comparable asbestos samples.  

Injured cells normally release chemical beacons that signal a cell's distress and induce an inflammatory response from the immune system. This response could include the release of white blood cells and other immune soldiers to help fight invaders.

In this study, the normal inflammatory response of two lung cell types was suppressed after they were exposed to SWCNT. The immune response was diminished in both healthy cells and those responding to infection.

The toxic effect increased when the nanotubes were mixed in fluid similar to that found in lungs. The SWCNT's were more harmful because they moved more easily through the lung liquid than they did through a cell culture solution. The lung liquid simulates real-life conditions and shows how the particles might behave in a lung.